Review of the trilobites from the Middle Ordovician Barr Group, Girvan district, Scotland

Abstract

AbstractCollections from the Barr Group (late Llanvirn to early Caradoc) of the Girvan district are described and occurrences of all trilobites from both the Barr and Albany groups are listed and their frequencies recorded. The close relationships with North American faunas are emphasised, and three Girvan and North American species are considered synonymous. One new species is described, Bevanopsis phyllisae. Pandaspinapyga is considered a junior subjective synonym of Acanthoparypha. The possibility that Alwynulus may be an aberrant staurocephalid is discussed.Growth stages of several genera are illustrated; some show unexpectedly large differences in size and morphology in comparison with North American silicified species at the same general stage of development.